Power monitors are used to measure and track the power that is supplied to electronic devices via a power supply. Power supplies are designed to provide regulated levels of power to an electronic device, but significant deviations in the actual power output of a power supply occur regularly. These deviations in the output of a power supply can be categorized into two general categories. The first type are brief, unintended surges or spikes in the current drawn by the peripheral device being powered by the supply. These transient spikes can have a wide range of causes and can potentially be damaging. A second type of deviations are sustained increases in the current drawn on the power supply. This second type of deviation is sometimes the result of intended, temporary increases in the output of the power supply.
The first type of deviation occurs when the current drawn by the electronic device surges and results in a transient spike in the power output of the supply. Power supplies typically include circuitry to prevent such spikes that surpass a magnitude that could cause damage to components of the device circuitry. Even relatively minor power surges that do not trigger the circuit protection components of a power supply can still result in damage due to their cumulative effects. Detecting and measuring these events can provide information useful for diagnosing the cause of the surges, especially during the electronic device's development phase.
The second type of deviation may occur due to a malfunction, but will frequently occur by design in certain devices. In high performance portable computing products (e.g., smartphones, tablets, netbooks and laptops), power supplies typically include features that allow for elevated power levels to be provided. Power supplies are provided with specifications that define 100% power output for the supply. Certain devices also provide a “turbo” mode, that allows the power supply to exceed 100% output levels for a specified amount of time. For instance, a power supply that supports turbo mode can provide (100+X)% power over Y period of time, where X and Y are power supply dependent. As with the first type of event, these prolonged deviations in power output can result in damage to the device over time. Consequently, monitoring the duration and frequency of such events provides designers with information that can be used to anticipate possible damaging side-effects and to promote long-term reliability.
The physical overstress resulting from both types of deviations may cause failure over time and any effects of such damage must be addressed. However, these two types of deviations differ in that certain of the prolonged violations are by design. As a result, it is advantageous to differentiate between these two types of deviations in the power supply output. It is also advantageous to provide information describing each deviation, with the information tailored to the type of deviation that is observed. Such information is especially helpful during the development cycle, when identification of a component suffering from power malfunctions must be identified. Any information captured by the power monitor describing a power malfunction can be used to diagnose the offending component causing the malfunction.
Conventional power monitors do not provide the ability to effectively detect and measure the excessive current drawn during both types of deviations. Instead, conventional systems tend to approximate the magnitude of deviations in the power supply output based on information such as temperature measurements. Not only are such approximations unreliable in discerning actual deviations in the output of the power supply, they do not provide accurate information regarding the magnitude and duration of deviations. The lack of reliable and accurate information precludes effective diagnosis of the underlying issues that cause the deviations.